Is Parkinson's Disease Genetic or Hereditary?

Most cases of Parkinson’s disease are not strictly hereditary. Approximately 85% to 90% of Parkinson’s cases are idiopathic, meaning they occur sporadically without a known cause or clear family history ^[1][2]. However, genetics do play a role, and about 10% to 15% of cases are directly linked to specific genetic variations ^[1]. If you have been diagnosed with idiopathic Parkinson’s, the risk of your children developing the disease is only slightly higher than the general population’s baseline risk, meaning their overall risk remains very low ^[3].

Idiopathic vs. Genetic Parkinson’s

When researchers study Parkinson’s, they generally divide it into two categories:

• Idiopathic Parkinson’s Disease: This is the most common form. While first-degree relatives (like children or siblings) have a slightly increased risk of developing the disease compared to someone with no family history ^[3], there is no single “Parkinson’s gene” passed down that causes it. Instead, it is likely caused by a complex combination of minor genetic risks, age, and broad environmental factors (such as a history of head injury or long-term exposure to certain agricultural pesticides) ^[3].
• Genetic (Familial) Parkinson’s Disease: A smaller percentage of cases are caused by inherited genetic mutations ^[1]. These cases are often associated with a strong family history or early-onset Parkinson’s disease (diagnosed before age 50) ^[4][5].

Key Genes Associated with Parkinson’s

Researchers have identified several specific genes that are linked to Parkinson’s disease. The most common ones include:

• LRRK2 (Leucine-rich repeat kinase 2): Mutations in this gene are a prominent genetic risk factor ^[6]. They are particularly common in people of Ashkenazi Jewish or North African Berber descent ^[7]. LRRK2 is an autosomal dominant gene, meaning a parent only needs to pass down one copy for their child to inherit the mutation ^[6]. However, the LRRK2 gene has incomplete penetrance ^[8]. This means that even if someone inherits the mutated gene, their lifetime risk of actually developing Parkinson’s is often less than 50% ^[8].
• GBA (Glucocerebrosidase): This is considered a genetic “risk factor” or susceptibility gene, rather than a direct cause ^[9]. Like LRRK2, GBA mutations have low penetrance, meaning many people who carry the mutation will never develop the disease ^[10]. The mutation affects how cells manage waste, which can sometimes encourage the buildup of proteins associated with Parkinson’s ^[11], but the presence of the gene alone is usually not enough to cause the disease.
• SNCA (Alpha-synuclein): Although rare, mutations in this gene were the first to be definitively linked to Parkinson’s disease ^[12]. Like LRRK2, it is an autosomal dominant gene.
• PRKN (Parkin) and PINK1: These genes are typically associated with early-onset Parkinson’s disease ^[12][13]. They are autosomal recessive, which means a child must inherit a mutated copy from both parents to develop the disease ^[12]. If they inherit only one, they are simply a carrier.

What This Means for Your Children

A top concern for parents upon diagnosis is whether they will pass the condition to their kids. The reality depends heavily on the type of Parkinson’s you have:

• If you have idiopathic Parkinson’s: There is no single genetic mutation to pass down. Your children’s risk is only slightly elevated above the average person’s risk, which means it remains a small possibility, not an expectation ^[3].
• If you have an autosomal dominant mutation (like LRRK2 or SNCA): There is a 50% chance you will pass the mutated gene to each child ^[8][12]. However, because of incomplete penetrance, even if they inherit the gene, their actual risk of developing the disease is lower than 50% ^[8].
• If you have an autosomal recessive mutation (like PRKN): You will pass one copy of the gene to your children. Unless your partner also carries a mutation in the exact same gene, your children will be carriers but are very unlikely to develop the disease ^[1][12].

Should You Consider Genetic Testing?

Understanding your genetic status is becoming increasingly relevant for clinical management. Knowing if you carry a specific mutation might eventually make you eligible for targeted clinical trials ^[14].

However, before pursuing testing, it is highly recommended that you speak with a genetic counselor ^[14][15]. Genetic counselors are specially trained professionals who can help you and your family understand inheritance patterns, assess your personal risk, and navigate the emotional and practical implications of genetic testing ^[14][16]. For example, while the Genetic Information Nondiscrimination Act (GINA) in the United States protects you from health insurance and employment discrimination based on genetic tests, it does not apply to life insurance or long-term care insurance ^[14]. A counselor will help you weigh these factors before you make a decision.